The
Rhinoceros Auklet is a large seabird, closely related to puffins. They
are named for the fleshy protuberance that grows on their upper mandible
each spring before the breeding season. The 'horn' is lost each fall,
only to regrow the following spring. Outside of the breeding season,
they are sometimes confused with the Tufted
Puffin, but the bill of a Rhinoceros Auklet is much less massive than a
puffin's bill at all seasons. Populations on some former breeding
colonies crashed after the accidental introduction of rodents. Active
efforts to remove all rats and rabbits from some islands have led to
successful recolonization of former nesting colonies.

Habitat: During the summer breeding season, found
on islands with suitable soil for digging nesting burrows. At other
seasons, tends to forage out at sea where upwelling currents concentrate
fish and other prey, but moves closer to shore to overnight in and around
protected coastal waters.

Diet: Feeds on fish and crustaceans such as shrimp
and amphipods..

Behavior: Feeds by diving and swimming underwater.

Nesting: The nest of a Rhinoceros Auklet is a
burrow, built in grassy areas with scattered rocks or trees. The
burrow may be up to 20 feet long, ending in a nesting chamber with a nest
built of mosses, seaweed and twigs. The female lays one egg per
season. Both the parents help to incubate the egg, and both parents
help feed the young upon hatching.

Song: On breeding colonies, low moaning calls and
shorter barking calls are heard. Outside of the breeding season, they
are mostly silent.

Migration: While some auks in the north Pacific
are relatively permanent residents, the Rhinoceros Auk is strongly
migratory. Most birds leave the northern part of their range in the
fall and move southward along the Pacific Coast.